docs: def verify_gpg_version():
      """Make sure that the installed GnuPG is not too old."""
      existing_gpg = keyring.gpg_version().decode('ascii')
      required_gpg = '>=2.1.11'
      msg = 'Existing GnuPG has version "{}" ({} required)'.format(existing_gpg,
                                                                   required_gpg)
      if not semver.match(existing_gpg, required_gpg):
          log.error(msg)